JP2013183982A - Ultrasonic diagnostic apparatus and elastic image generation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an elastic image capable of displaying a tissue elasticity response acquired on the basis of a pressure condition of the same size.SOLUTION: An ultrasonic diagnostic apparatus includes: an elasticity information calculation part 13 for obtaining elasticity information of an organism tissue in multiple measurement points within an image area and a measurement pressure condition of the multiple measurement points, on the basis of a reflection echo signal to be acquired by transmitting an ultrasonic wave from a probe; an image display unit 10 for displaying elastic images generated on the basis of elastic information; and a pressure condition evaluation part 18 for selecting elastic information for the generation of elastic images to be displayed in the image display unit in accordance with a measurement pressure condition at a current time or before the current time, and allowing the image display unit to display elastic images at the multiple measurement points generated on the basis of the selected elastic information at a current time and before the current time.

Description

  The present invention relates to an ultrasonic diagnostic apparatus and an elastic image generation method, and more particularly, to an ultrasonic diagnostic apparatus and an elastic image generation method for imaging a tissue elasticity measured by applying pressure to a living tissue of a subject and using it for diagnosis. .

  The ultrasonic diagnostic apparatus applies an ultrasonic probe to the surface of the subject, transmits ultrasonic waves from the probe to the subject, receives ultrasonic reflected waves from the inside of the subject, and receives the received signal. Based on the reflected echo signal, the biological information of each part of the subject is displayed as an image such as a tomographic image for diagnosis.

  On the other hand, as described in Patent Documents 1 and 2, etc., information relating to elasticity (hereinafter referred to as elasticity information) such as tissue strain and elastic modulus generated inside by applying a compression force to the subject is obtained. An elastic image is generated, and the elastic image is displayed to be used for diagnosis of a lesioned part of an examiner. For example, the examiner distinguishes lesions such as normal tissues, cancer cells, and tumors by observing elastic images measured while adjusting the compression force.

  By the way, it is known that a living tissue exhibits a non-linear elastic response to compression, and the hardness changes according to the degree of compression such as the amount of compression (hereinafter referred to as compression condition). For example, Non-Patent Document 1 reports an actual measurement value of the relationship between stress (kPa) and strain (%) when a mammary gland region and a fat region of a mammary gland tissue are compressed as shown in FIG. According to the figure, the stress-strain in the fat region is a linear relationship, but the stress-strain relationship in the mammary gland region is non-linear. Therefore, the elastic modulus (Young's modulus) given by the slope of the stress-strain curve in FIG. 8 is a constant value in the fat region, as shown schematically in FIG. 9, but in accordance with the applied strain in the mammary region. It can be seen that changes.

  On the other hand, in Non-Patent Document 2, after acquiring data on the relationship between strain and elastic modulus, a strain-elastic modulus curve is approximated by a function, and the nonlinearity is expressed from a curve that is best approximated by a least square method or the like. Attempts have been made to extract parameters and evaluate them as information representing the nonlinearity of the tissue.

JP-A-5-317313 JP 2000-60853 A

krouskop T, et al: Elastic Moduli of Breast and Prostate TissuesUnder Compression. Ultrasonic Imaging 20: 260-274, 1998. “Imaging Nonlinear Elastic Properties of Tissues by Ultrasound” Nitta et al., IEICE Transactions 2001/12 Vol. J84-A No.1

  Thus, in distinguishing benign and malignant tissue using tissue hardness information, for example, under what compression conditions the elastic modulus was measured is very important information, such as compression amount It may be considered that benign and malignant are erroneously diagnosed with respect to a diagnosis target measured under conditions in which the compression conditions are greatly different.

However, the conventional techniques described in Patent Documents 1 and 2 do not consider the non-linearity of the biological tissue whose hardness changes according to the degree of compression.
In other words, since the elasticity of the living tissue has non-linearity, it is considered that a correct evaluation cannot be performed unless the comparison is performed using the elasticity information obtained under the compression condition of the same size.

  It is an object of the present invention to provide an elastic image that allows a response of tissue elasticity obtained based on a compression condition of the same size to be displayed in an ultrasonic diagnostic apparatus.

  In order to solve the above-described problem, the ultrasonic diagnostic apparatus of the present invention is based on a reflected echo signal obtained by transmitting an ultrasonic wave from a probe, and information on the elasticity of biological tissue at a plurality of measurement points in an image region. And an elasticity information calculation unit for obtaining measurement compression conditions for the plurality of measurement points, an image display for displaying an elasticity image generated based on the elasticity information, and generating the elasticity image to be displayed on the image display The elasticity information for the current measurement time is selected according to the measurement compression condition at the current time or before the current time, and at the plurality of measurement points generated based on the selected current time and the elasticity information before the current time. And a compression condition evaluation unit that displays an elastic image on the image display.

  ADVANTAGE OF THE INVENTION According to this invention, the elasticity image which makes it possible to display the response | compatibility of the tissue elasticity obtained based on the compression conditions of the same magnitude | size can be provided.

It is a block block diagram of the ultrasonic diagnostic apparatus of one Embodiment which implements the elasticity image generation method of this invention. It is a figure which shows the B mode image of the site | part containing the biological tissue which applies compression and produces | generates an elastic image. It is an example of the elasticity image produced | generated in Example 1, and is a figure which shows the image of the state which only the periphery of ROI satisfy | fills the representative measurement compression conditions, and is gradation-ized by the monochrome luminance. It is an example of the elasticity image produced | generated in Example 1, and it is the same as the stress loaded in ROI not only in the area | region where the stress of the present time satisfy | fills representative measurement compression conditions, but the area | region which does not satisfy representative measurement compression conditions It is a figure which shows the image of the state in which the value of the Young's modulus obtained on compression conditions was mapped. When the elastic image generated in the first embodiment is generated, the stress at the current time does not satisfy the representative measurement compression condition, but the region where the stress before the current time satisfies the representative measurement compression condition is loaded in the ROI. It is a figure which shows the image of the state in which the value of the Young's modulus obtained on the same compression conditions as stress was mapped. (a) to (c) are the movement states of the tissue belonging to the ROI when the position of the ROI is fixed with respect to the image, and (d) to (f) are the destinations of the tissue belonging to the ROI. It is a figure for demonstrating the state which moved ROI so that it may track according to a grade. It is a figure which shows the graph image which displayed the relationship between the stress and elastic modulus of the biological tissue produced | generated in Example 2, and displayed the slide bar for setting a reference | standard compression condition. It is a figure which shows the relationship between the distortion at the time of compressing the mammary gland part and fat part of a mammary gland tissue. It is a figure which shows typically the relationship between the distortion at the time of compressing the mammary gland part of a mammary gland tissue, and a fat part, and an elasticity modulus (Young's modulus).

  Hereinafter, an ultrasonic diagnostic apparatus and an elastic image generation method according to the present invention will be described with reference to the accompanying drawings. FIG. 1 is a block diagram of an ultrasonic diagnostic apparatus according to an embodiment that implements the elastic image generation method of the present invention. As shown in FIG. 1, an ultrasonic probe 2 used in contact with a subject 1 is formed with a plurality of transducers that transmit and receive ultrasonic waves to and from the subject 1. Yes. The probe 2 is driven by ultrasonic pulses supplied from the transmission circuit 3. The transmission / reception control circuit 4 controls the transmission timing of ultrasonic pulses for driving the plurality of transducers of the probe 2 to form an ultrasonic beam toward the focal point set in the subject 1. ing. The transmission / reception control circuit 4 is configured to electronically scan the ultrasonic beam in the direction in which the transducers of the probe 2 are arranged.

  On the other hand, the probe 2 receives a reflected echo signal generated from the subject 1 and outputs it to the receiving circuit 5. In accordance with the timing signal input from the transmission / reception control circuit 4, the reception circuit 5 takes in the reflected echo signal and performs reception processing such as amplification. The reflected echo signal processed by the receiving circuit 5 is amplified by adding together the phases of the reflected echo signals received by the plurality of transducers in the phasing and adding circuit 6. The reflected echo signal phased and added in the phase adjusting and adding circuit 6 is input to the signal processing unit 7 and subjected to signal processing such as gain correction, log compression, detection, contour enhancement, and filter processing.

  The reflected echo signal processed by the signal processing unit 7 is guided to the monochrome scan converter 8 and converted into two-dimensional tomographic image data (digital data) corresponding to the scanning surface of the ultrasonic beam. These signal processing unit 7 and monochrome scan converter 8 constitute a tomographic image (B-mode image) image reconstruction means. The tomographic image data output from the black-and-white scan converter 8 is supplied to the image display 10 via the switching addition unit 9, and a B-mode image as shown in FIG. 2 is displayed.

  On the other hand, the reflected echo signal output from the phasing addition circuit 6 is guided to the frame data acquisition unit 11. The frame data acquisition unit 11 acquires frame data of a reflected echo signal obtained by applying pressure to the living tissue of the subject 1 and transmitting ultrasonic waves from the probe 2. That is, the frame data acquisition unit 11 acquires a plurality of frames of reflected echo signal groups corresponding to the scanning plane (tomographic plane) of the ultrasonic beam as frame data, and stores it in a memory or the like. The displacement measuring unit 12 sequentially captures a plurality of pairs of frame data with different acquisition times stored in the frame data acquiring unit 11, and obtains displacement vectors of a plurality of measurement points on the tomographic plane based on the captured pair of frame data. The displacement information is output to the elasticity information calculation unit 13 as displacement frame data.

Based on the reflected echo signal obtained by transmitting an ultrasonic wave from the probe 2, the elasticity information calculation unit 13 is based on the elasticity information of the biological tissue at a plurality of measurement points in the image region and the measurement compression conditions for the plurality of measurement points. (Condition indicating the degree of compression applied to the measurement point). More specifically, the elasticity information calculation unit 13 obtains the measurement compression condition based on the frame data acquired by the frame data acquisition unit 11. In the present embodiment, the elasticity information calculation unit 13 calculates a strain calculation unit for obtaining a strain change of the biological tissue at each measurement point based on the displacement frame data, and calculates an elastic modulus of the biological tissue at each measurement point based on the strain frame data. An elastic modulus calculation unit to be obtained, an integrated strain calculation unit to obtain a strain that is an example of a measurement compression condition by integrating the strain change obtained by the strain calculation unit, and a measurement compression condition based on the pressure obtained by the pressure measurement unit 17 As an example, the apparatus includes a stress calculation unit that obtains stress (distribution) inside the subject. The elastic modulus frame data obtained by the elastic information calculation unit 13 is output to the elastic information processing unit 14, and the strain and stress (distribution) are output to the compression condition evaluation unit 18.
Here, the method for obtaining the stress (distribution) is arbitrary, and is not limited to the pressure sensor, and many known methods such as a method for obtaining the surface pressure using an acoustic coupler or the like and estimating the stress using a finite element method or the like. There is an example.

  The elasticity information processing unit 14 performs various processes such as smoothing processing in the coordinate plane, contrast optimization processing, and smoothing processing in the time axis direction between frames on the frame data of each elasticity information input from the elasticity information calculation unit 13. The image is processed and sent to the color scan converter 15.

  The color scan converter 15 takes in the elastic modulus frame data processed by the elastic information processing unit 14 and generates a color elastic image by assigning a tone code to each pixel of the frame data in accordance with the color map of the set elastic modulus. It is supposed to be.

  The color elasticity image generated by the color scan converter 15 is displayed on the image display 10 via the switching addition unit 9 as shown in FIG. The switching adder 9 also receives a black and white tomographic image output from the black and white scan converter 8 and a color elastic image output from the color scan converter 15 and switches both images to display one of them. In addition, one of the two images is translucent, added and combined, displayed on the image display 10 and displayed, and the two images are displayed side by side. Further, the image data output from the switching addition unit 9 is stored in the cine memory unit 20 under the control of the device control interface unit 19. The image data stored in the cine memory unit 20 is displayed on the image display 10 under the control of the device control interface unit 19. As described above, the image display 10 displays the elasticity image generated based on the elasticity information so that the subject can visually recognize the elasticity image.

  The compression condition evaluation unit 18 generates elasticity information for generating an elasticity image to be displayed on the image display 10 at the current time or before the current time (any time that goes back in the past from the current time, hereinafter referred to as the past). The image display 10 displays an elasticity image at a plurality of measurement points selected based on the measurement compression condition and generated based on the selected current time and past elasticity information. More specifically, the compression condition evaluation unit 18 sends a command to the elastic information processing unit 14 based on the selected current time and past elastic information, and at a plurality of measurement points generated by the color scan converter 15. A color elastic image is output and displayed on the image display 10.

  The basic operation of this embodiment configured as described above will be described. First, the probe 2 applies pressure to the subject 1 to scan the subject 1 with an ultrasonic beam, and continuously receives reflected echo signals from the scanning surface. Based on the reflected echo signal output from the phasing addition circuit 6, the tomographic image is reconstructed by the signal processing unit 7 and the black and white scan converter 8 and displayed on the image display 10 via the switching addition unit 9. .

  On the other hand, the frame data acquisition unit 11 takes in the reflected echo signal, repeatedly acquires the frame data in synchronization with the frame rate, and stores it in the built-in frame memory in chronological order. Then, a plurality of pairs of frame data are successively selected and output to the displacement measuring unit 12 with a pair of frame data having different acquisition times as a unit. The displacement measuring unit 12 performs one-dimensional or two-dimensional correlation processing on the selected pair of frame data, measures the displacement of a plurality of measurement points on the scanning plane, and generates displacement frame data. As a method for detecting the displacement vector, for example, a block matching method or a gradient method described in JP-A-5-317313 is known. In the block matching method, an image is divided into blocks of N × N pixels, for example, a block closest to the target block in the current frame is searched from the previous frame, and based on this, the displacement of the measurement point is determined. Ask. Further, the displacement can be calculated by calculating the autocorrelation in the same region of the pair of RF signal frame data.

  The elasticity information calculation unit 13 takes in the displacement frame data, obtains a strain change at each measurement point, calculates an elastic modulus that is elasticity information based on the obtained strain change, and obtains the elasticity frame data as an elastic information processing unit 14. Output to. The calculation of the strain change is calculated by spatially differentiating the displacement as is well known. Further, the elastic modulus at each measurement point is calculated based on the obtained strain change. When calculating | requiring an elasticity modulus, the measured value of the pressure measured by the pressure measurement part 17 is taken in, and the stress in each measurement point is calculated based on this. The pressure measurement unit 17 calculates the stress at the measurement point inside the subject 1 based on the pressure detected by the pressure sensor 16 provided between the ultrasonic transmission / reception surface of the probe 2 and the subject 1. . That is, the elastic modulus calculation unit of the elastic information calculation unit 13 calculates the elastic modulus E (for example, Young's modulus) of each measurement point on the scanning surface from the stress at each measurement point and the strain frame data obtained by the elastic information calculation unit 13. Is calculated and output to the elastic information processing unit 14.

  The elastic information processing unit 14 performs processing such as smoothing processing on the input elastic modulus and outputs the processed elastic modulus to the color scan converter 15. The color scan converter 15 generates a color elasticity image based on the elasticity information. For example, the color image is colored according to the elastic modulus of the frame data for each pixel unit with a gradation of color tone by 256 gradations. In place of the color scan converter 15, a black and white scan converter can be used. In this case, it is possible to discriminate benign or malignant, for example, by increasing the luminance in a region having a large elastic modulus and conversely decreasing the luminance in a small region.

  A specific embodiment for generating an elastic image in the ultrasonic diagnostic apparatus of the present invention will be described below. Each embodiment is implemented by the elastic information calculation unit 13, the elastic information processing unit 14, the compression condition evaluation unit 18, the device control interface unit 19, the cine memory unit 20, and the like, which are characteristic parts of the present invention.

  As an embodiment of the elastic image generation method of the present invention, a case will be described in which an elastic image is generated by applying pressure to a part including the living tissue shown in the B-mode image of FIG. In the first embodiment, the elastic modulus obtained as the elastic frame data in the elastic information calculation unit 13 is used as the elastic information of the measurement point in each part of the living tissue. As elastic information, in addition to the elastic modulus, a viscoelastic modulus, a nonlinear parameter related to the nonlinearity of the elastic modulus, hysteresis, and the like can be assumed.

First, a region of interest (hereinafter referred to as ROI) is input and set to the compression condition evaluation unit 18 by the examiner from the device control interface unit 19. At that time, the ROI is set in an image region corresponding to the frame data acquired by the frame data acquisition unit 11, and the target image may be a B-mode image shown in FIG. 2 or an elastic image shown in FIG. . For example, FIG. 2 shows a state in which an image corresponding to a tomographic image of black and white luminance in the subject is displayed, and the ROI is set so that the living tissue 22 shown in the tomographic image belongs. . 3 shows a state in which an image corresponding to the color elastic image corresponding to the scanning plane in FIG. 2 is displayed, and the biological tissue 32 (the biological tissue 22 shown in FIG. 2) shown in the elastic image. The ROI is set so that the
Next, the compression condition evaluation unit 18 takes in elastic modulus data (numerical data of elastic modulus) at each measurement point from the elastic information calculation unit 13 as elastic information and measures and compresses numerical data such as stress and strain at each measurement point. Capture as a condition. In Example 1, a case where stress is used as a measurement compression condition for evaluating the degree of compression is shown.
And the compression condition evaluation part 18 selects the elasticity information for producing | generating the elasticity image displayed on the image display 10 from the elasticity information of the present time in a measurement point. In addition, the compression condition evaluation unit 18 generates elasticity information for generating an elasticity image to be displayed on the image display 10 according to the measurement compression condition at the current time at the measurement point where the elasticity information is selected. A selection is made for each measurement point from the current time or past elasticity information at the measurement point that was not selected. For example, when generating an elasticity image, a plurality of elasticity information at the current time is selected for each measurement point from the measurement points included in the ROI, and the current time or past elasticity information is measured from the measurement points not included in the ROI. Multiple selections are made for each.

As one aspect of the first embodiment, a case where the stress applied to the ROI is obtained and an image in the ROI and an image of an area other than the ROI are generated based on the elasticity information obtained under the stress will be described. .
In this case, the compression condition evaluation unit 18 obtains a representative measurement compression condition representative of the measurement compression condition from the measurement compression condition (for example, stress) obtained by the elasticity information calculation unit 13, and obtains the current time or the past at the measurement point. To determine whether or not the measurement compression condition satisfies the representative measurement compression condition, and to generate an elasticity image of the current time or past elasticity information (elastic modulus data) for each measurement point that satisfies the representative measurement compression condition Select as information. The representative measurement compression condition is a stress condition representative of the measurement compression condition obtained by the elasticity information calculation unit 13, and the stress taken into the compression condition evaluation unit 18 from the elasticity information calculation unit 13 is a biological tissue. This is a threshold for determining whether or not the elasticity information (such as the elastic modulus obtained by the elasticity information calculation unit 13) should be imaged.

In Example 1, the compression condition evaluation unit 18 measures the measured elastic modulus (for example, Young's modulus) and the stress interval at the time of measurement (the stress indicated by the upper limit value and the lower limit value) for each of all measurement points. Information indicating the correspondence relationship of the range) (hereinafter referred to as Young's modulus-stress correspondence information) is stored.
For example, the stress interval is set as stress intervals 1 to 10 obtained by dividing 10 from 0 to 1 kPa, and the values of Young's modulus obtained in the respective stress intervals at the measurement point Pi, j are expressed as Ei, j, Represented by m. Note that in Ei, j, m, i, j is the position of the measurement point Pi, j (for example, the coordinate position of the pixel 30 shown in FIG. 3), and m is a parameter indicating the stress interval.
Ei, j, 1: Young's modulus obtained under conditions of stress 0 kPa or more and less than 0.1 kPa Ei, j, 2: Young's modulus obtained under conditions of stress 0.1 kPa or more and less than 0.2 kPa
Ei, j, 9: Young's modulus obtained under conditions of stress 0.8 kPa or more and less than 0.9 kPa Ei, j, 10: Young's modulus obtained under conditions of stress 0.9 kPa or more and less than 1.0 kPa

  In the first embodiment, the representative measurement compression condition is obtained based on the average value of the stress at the current time at the measurement point in the ROI. Therefore, the compression condition evaluation unit 18 obtains stress as the size of the compression applied to the ROI region at the current time. For example, it is assumed that a stress interval including an average value of stress applied to a measurement point in the ROI at the current time is a representative measurement compression condition, and this average value is obtained as σroi (0) = 0.86 kPa. The stress σ roi (0) in the ROI corresponding to the obtained representative measurement compression condition and the value of the Young's modulus at that time are displayed numerically on the B-mode image shown in FIG. 2 or the elastic image shown in FIG. By doing so, the examiner can easily grasp these.

When the representative measurement compression condition is thus obtained, the compression condition evaluation unit 18 is obtained under a stress that matches the magnitude of the stress σroi (0) (in other words, the stress σroi (0) A value of Young's modulus (corresponding to a stress section including) is obtained with reference to the Young's modulus-stress correspondence information.
For example, since the stress of 0.86 kPa corresponds to the stress section 9, referring to the value of Ei, j, 9 (0) as the Young's modulus at each measurement point Pi, j, The value of the Young's modulus at each measurement point Pi, j can be obtained. Then, for each measurement point Pi, j, the Young's modulus is mapped by giving gradation to the monochrome luminance or hue according to the obtained value.

  However, even if the stress at the current time at a certain measurement point has a value corresponding to the representative measurement compression condition (hereinafter, this state is referred to as the representative measurement compression condition), the stress at the current time at another measurement point. May not be a value corresponding to the representative measurement compression condition (it is said that the representative measurement compression condition is not satisfied). For example, at the measurement point Pi, j, if the stress at the current time is not less than 0.8 kPa and less than 0.9 kPa (the stress is not in the stress section 9), Ei, j, 9 (0) has a Young's modulus. The value is not obtained. That is, there is no correspondence information of Young's modulus-stress to be referred to. In this case, neither the monochrome luminance nor the hue is given to the image of the Young's modulus at the measurement point Pi, j.

  FIG. 3 shows an example of mapping display of such Young's modulus. The value of Young's modulus at the measurement point Pi, j in the subject is a color tone for each pixel 30 corresponding to the measurement point Pi, j. It is displayed as a color image with a code attached. In this case, the ROI is set so that the living tissue 32 (corresponding to the living tissue 22 shown in FIG. 2) belongs, and the pixel 30 corresponding to the measurement point Pi, j that satisfies the representative measurement compression condition at the current time is the value of Young's modulus. Color display is based on. That is, in the elasticity image shown in FIG. 3, the Young's modulus of the measurement point that satisfies the representative measurement compression condition at the current time is selected as elasticity information for generating the elasticity image, and the measurement based on the value of the selected Young's modulus. The pixel 30 corresponding to the point is an image displayed in color. At that time, a measurement point that does not satisfy the representative measurement compression condition at the current time is not selected as elasticity information for generating an elasticity image.

As an example, in FIG. 3, the corresponding pixel 30 is displayed in a darker color at the measurement point Pi, j having a larger Young's modulus value. In FIG. 3, for the sake of convenience, black and white shading is given to each pixel 30 according to the Young's modulus, but a color image with a tone code assigned to each pixel 30 is displayed on the actual screen. Is done.
Therefore, according to the display image of FIG. 3, the region corresponding to the living tissue 32 (the region shown in the darkest color in the drawing) is the surrounding tissue (shown in the drawing) of the living tissue 32 under the representative measurement compression condition. It is possible to grasp that the Young's modulus is higher at the current time than the regions 34 and 36, which are lighter than the living tissue 32. On the other hand, the surrounding tissues 34 and 36 of the living tissue 32 have a Young's modulus lower than that of the living tissue 32 at the current time including the overlapping area with the ROI, and the surrounding tissues 34 and surrounding tissues as the distance from the living tissue 32 increases. It can be seen that the Young's modulus gradually decreases in the order of 36. Further, tissues other than the living tissue 32 and the surrounding tissues 34 and 36 (regions shown in white in FIG. 3) do not satisfy the representative measurement compression conditions at the current time, and the measurement within the tissue is not performed. It can be understood that the value of the Young's modulus at the point is not measured.
In this way, an elastic image based on the value of Young's modulus obtained under the same stress as the current time stress σroi (0) loaded on the ROI can be generated and displayed in real time.

  Here, in the above-described aspect (hereinafter referred to as aspect 1-1), since an elastic image is generated based on the Young's modulus value at the measurement point that satisfies the representative measurement compression condition at the current time, the stress at the current time is generated. However, the measurement points that do not satisfy the representative measurement compression condition may not be displayed with gradation in black and white luminance or hue. Therefore, not only the current time but also information on the elastic modulus (as an example, Young's modulus) of the measurement point in the past is stored, and an elastic image can be generated based on the stored information (Example 1) Hereinafter, Mode 1-2 will be described.

In this case, a buffer or the like that can store a plurality of past measurement results in addition to the measurement result at the current time is defined. As an example, the current time for each stress section at the measurement point Pi, j and the measurement results up to the past 10 times are represented by Ei, j, m (n) as follows. In Ei, j, m (n), i, j is the position of the measurement point Pi, j (for example, the coordinate position of the pixel 30 shown in FIG. 3), m is the stress interval, and n is the past Young's modulus measurement. Each parameter indicates how many times before the current time the measurement was obtained.
Ei, j, 1 (0): Measurement result of Young's modulus obtained by measurement at the current time in stress section 1 at measurement point Pi, j Ei, j, 1 (1): Stress at measurement point Pi, j Measurement result of Young's modulus obtained in measurement 1 time before current time in section 1 Ei, j, 1 (2): Measurement at measurement point Pi, j twice before current time in stress section 1 Measurement result of Young's modulus obtained in ...
Ei, j, 1 (10): Measurement result of Young's modulus obtained by measurement 10 times before the current time in stress section 1 at measurement point Pi, j
Then, at all measurement points Pi, j, the past Young's modulus measurement results obtained in each of the plurality of assigned stress sections are stored in a buffer and can be referred to. For example, when the stress interval is 10 intervals similar to the above-described aspect 1-1, the Young's modulus values of the measurement points Pi, j at 11 points in the current time and the past 10 measurements are 110 in total for each stress interval. Pattern can be saved.

  As described above, in aspect 1-1, the stress at the measurement point Pi, j at the current time does not correspond to the stress interval corresponding to the magnitude of the stress σroi (0) in the ROI at the current time (that is, representative measurement compression) If the condition is not satisfied, the Young's modulus value at the measurement point Pi, j cannot be obtained. On the other hand, in this aspect 1-2, if the stress value satisfying the representative measurement compression condition at the present time is measured in the past measurement and the Young's modulus value obtained in the stress interval is stored, the Young An image based on the rate value can be displayed.

  For example, it is assumed that the average value of stress loaded in the ROI at the current time is σroi (0) = 0.86 kPa. As the Young's modulus at the measurement point Pi, j, whether or not the value obtained in the past measurement is stored in the stress section 9 is searched, and if it is stored, the latest result (the latest Young's modulus) is used. A value of Ei, j, 9 (1) is referred to, and mapping of the Young's modulus is performed with gradation in black and white luminance or hue according to the value. In addition, when mapping is performed for the current time or the latest Young's modulus in this way, if the stress interval is 10 intervals similar to the above-described aspect 1-1, the current time and 2 points in the past measurement are measured. A buffer capable of storing a total of 20 patterns of Young's modulus values of the measurement points Pi, j for each stress section may be defined. That is, such a buffer definition can be changed as appropriate according to the mapping of Young's modulus.

  As described above, in this aspect 1-2, not only the region where the stress at the current time satisfies the representative measurement compression condition but also the region where the representative measurement compression condition is not satisfied, the same compression condition as the stress loaded in the ROI It is possible to generate a single image in which Young's modulus values obtained under (representative measurement compression conditions) are mapped. Therefore, it is possible to generate and display an elastic image based on the Young's modulus value for the entire region of the display image (observation image) including the ROI. In other words, in this case, the measurement result of the current time or the past Young's modulus at each measurement point Pi, j obtained under the same compression condition (representative measurement compression condition) is mapped for all measurement points. The image is synthesized with the image.

  FIG. 4 shows a display example of the image generated in this way, and the Young's modulus value at the measurement point Pi, j in the subject is determined for each pixel 30 corresponding to the measurement point Pi, j. It is displayed as a color image with a color code added. In this case, the ROI is set so that the living tissue 32 (corresponding to the living tissue 22 shown in FIG. 2) belongs, and the pixel 30 corresponding to the measurement point satisfying the representative measurement compression condition at the current time or the measurement point satisfied in the past. Color display is based on the Young's modulus value. In FIG. 4, as an example, the corresponding pixel 30 is displayed in a darker color at the measurement point Pi, j having a larger Young's modulus value. In FIG. 4, for convenience, black and white shading is given to each pixel 30 according to the Young's modulus, but a color image to which a tone code is assigned to each pixel 30 is displayed on the actual screen. Is done.

  Here, the elasticity image shown in FIG. 4 is the elasticity image shown in FIG. 3 generated in the above-described aspect 1-1, that is, the pixel 30 corresponding to the measurement point that satisfies the representative measurement compression condition at the current time has a Young's modulus. The image displayed in color based on the value and the image of the elastic image shown in FIG. 5, that is, the pixel 30 corresponding to the measurement point satisfying the representative measurement compression condition in the past was displayed in color based on the Young's modulus value. This corresponds to a state in which images are synthesized and imaged. Therefore, in such imaging, the elastic image data shown in FIG. 4 may be sent to the color scan converter 15 and displayed on the image display device 10 via the switching addition unit 9. Can also be imaged. In this case, the compression condition evaluation unit 18 sends a command to the elastic information processing unit 14 to send the image data of the elastic image shown in FIG. 3 and the image data of the elastic image image shown in FIG. 5 to the color scan converter 15. In the color scan converter 15, a color image is generated by assigning a tone code for each pixel 30 to each image data. Then, these generated color images may be added and combined by the switching addition unit 9 and displayed on the image display 10 in an overlapping manner.

As described above, in the elasticity image shown in FIG. 3, the Young's modulus of the measurement point that satisfies the representative measurement compression condition at the current time is selected as the elasticity information for generating the elasticity image, and the value of the selected Young's modulus is selected. The pixel 30 corresponding to the measurement point is an image in which color display is performed.
On the other hand, in FIG. 5, the representative measurement compression condition is not satisfied at the current time, but the Young's modulus at the measurement point satisfied in the past is selected and selected as elasticity information for generating an elasticity image. An image of an elastic image in which a color tone code is given to the pixel 30 corresponding to the measurement point based on the Young's modulus value is shown. However, the elastic image itself is not displayed on the image display 10. In this case, the area shown in white in FIG. 5 corresponds to the living tissue 32 and the surrounding tissues 34 and 36 (FIGS. 3 and 4), and this area satisfies the representative measurement compression condition at the current time. The color code is not assigned to the pixel 30 corresponding to the measurement point. On the other hand, two light-colored regions in FIG. 5 correspond to a part of the surrounding tissue 36 and the tissue 38 (FIGS. 3 and 4) other than the living tissue 32 and the surrounding tissues 34 and 36. The representative measurement compression condition is not satisfied at the current time, but since it has been satisfied in the past, the color code is assigned to the pixel 30 corresponding to the measurement point. In FIG. 5, a part of the surrounding tissue 36 and the entire region corresponding to the tissue 38 other than the living tissue 32 and the surrounding tissues 34 and 36 (FIGS. 3 and 4) satisfy the representative measurement compression condition in the past. The state is shown as an example. However, if a part of the region does not satisfy the representative measurement compression condition in the past, no color code is assigned to the pixel 30 corresponding to the measurement point.

  According to the display image shown in FIG. 4 generated in this way, the region corresponding to the living tissue 32 (the region shown in the darkest color in the drawing) is the region of the living tissue 32 under the representative measurement compression condition. It can be understood that the Young's modulus is higher than that of the surrounding tissues (regions shown in a lighter color than the living tissue 32 in the figure) 34, 36, 38. On the other hand, the surrounding tissues 34, 36, and 38 of the living tissue 32 have a lower Young's modulus than the living tissue 32 including the overlapping region with the ROI, and the surrounding tissues 34 and 36 are separated from the living tissue 32. It can be understood that the Young's modulus gradually decreases in the order of the surrounding tissue 38. As described above, in FIG. 4, the elasticity image based on the Young's modulus value is generated and displayed for the entire region of the display image (observation image) (the living tissue 32 and the surrounding tissues 34, 36, and 38). It is in a state.

In addition, in this aspect 1-2, as mentioned above, based on the value of the latest elasticity information (for example, Young's modulus) in each stress section obtained by past measurement at each measurement point Pi, j. Although the method for generating the image has been shown, the compression condition evaluation unit 18 smoothes the measurement result of the past elasticity information at the measurement point Pi, j where the elasticity information (for example, Young's modulus) is selected, or The measurement result of the current time and past elasticity information may be smoothed, and the elasticity image may be displayed on the image display 10 based on the elasticity information after the smoothing.
For example, it is assumed that an average value of Young's moduli at a plurality of points measured in the past in each stored stress interval is calculated, and imaging is performed based on the average value. Is assumed to be σroi (0) = 0.86 kPa (stress corresponding to the representative measurement compression condition). The average value Ei, j, 9 (mean) of past measurement results of Young's modulus obtained in the stress section 9 at the measurement point Pi, j is
Ei, j, 9 (mean) = (Ei, j, 9 (1) + Ei, j, 9 (2) + Ei, j, 9 (3) + ... + Ei, j, 9 (10)) / 10
Therefore, the mapping of the Young's modulus gradationd with the black and white luminance or hue according to this value may be performed. It should be noted that the buffer definition may be changed as appropriate depending on how far past measurement results are referred to.

Furthermore, if the value of Young's modulus at the current time is obtained in the corresponding stress section, the average value of the Young's modulus value at the current time and the stored measurement result of the past Young's modulus is obtained, and the average Imaging according to the value may be performed.
In addition, the imaging process is not limited to the above-described FIR (Finite-duration Impulse Response) type smoothing process, but is based on an IIR (Infinite-duration Impulse Response) type smoothing process. Alternatively, it may be a process for obtaining a median (median) of past Young's modulus measurement results.
Thus, by performing the smoothing process with the past elasticity information, it becomes possible to generate a more stable and highly accurate image of Young's modulus.

  In each aspect of the first embodiment described above, a method is shown in which the examiner sets a region of interest (ROI) and generates an elasticity image based on the stress loaded in the ROI (stress corresponding to the representative measurement compression condition). However, the compression condition evaluation unit 18 uses the elastic information (as an example, Young's modulus) for generating an elastic image to be displayed on the image display 10 as the measurement compression condition at the current time at all measurement points in the image area. It is also possible to select for each measurement point from the current time or past elasticity information at all the measurement points according to (as an example, stress). That is, the entire area of the elastic image displayed on the image display 10 (that is, the entire area of the image being observed) is ROI, and the stress in the entire area (for example, the average stress applied to the measurement points in the entire area) The elastic image may be generated based on the (value). In this case, it is not particularly necessary to set the ROI. For example, particularly in the case where the position of the ROI is not fixed, such as a test for screening a wide area for a suspected site such as a tumor, the test efficiency can be improved.

Moreover, in each aspect of Example 1 mentioned above, it does not consider about the biological tissue which belongs to ROI moving by compression operation. Therefore, another aspect of the first embodiment (hereinafter referred to as aspect 1-3) that can improve the evaluation accuracy of the elasticity information by moving the ROI following the living tissue that is moved by the compression operation. explain.
For example, if the position of the ROI with respect to the image is fixed, the living tissue belonging to the ROI may change with the passage of time of the compression operation, and the accuracy of measurement values such as Young's modulus will deteriorate. That is, as shown in FIGS. 6A to 6C, when the compression operation on the living tissue 62 is performed from time t0 to time t2, the ROI is set so as to belong to the living tissue 62 at the time t0. (The state of ROI (t0) shown in FIG. 4A). Thereafter, with the passage of time of the compression operation, the ROI starts to shift toward the living tissue 64 due to the movement of the living tissue 62, and not only the living tissue 62 but also the living tissue 64 belongs to the ROI at the time t1 (FIG. State of ROI (t1) shown in FIG. At time t2, in addition to the living tissue 64, the living tissue 66 also belongs to the ROI (state of ROI (t2) shown in FIG. 10C).

For this reason, in this aspect 1-3, according to the degree of compression, by moving the ROI following the movement destination of the living tissue belonging to the ROI, only information on the same living tissue is obtained under an arbitrary compression condition. Extraction is possible. That is, as shown in FIGS. 6D to 6F, even when the compression operation to the living tissue 62 is performed from time t0 to time t2, the movement of the living tissue 62 over time is followed. By moving the ROI to the positions of ROI (t0), ROI (t1), and ROI (t2), only the living tissue 62 always remains in the ROI (from FIG. 6 (d) to ( State shown in f).
As a result, it is possible to improve the evaluation accuracy of elasticity information (for example, Young's modulus). In addition, what is necessary is just to apply the block matching method or the gradient method which calculates | requires the displacement vector of the biological tissue mentioned above to the process which follows the motion of a biological tissue and moves ROI. Further, even when the entire region of the display image (observation image) is an ROI, it can be followed according to the movement of the living tissue.
At that time, smoothing processing may be performed such as calculating an average value of past Young's modulus measurement results at the same tissue point.
Further, in the case of the new update process, it is necessary to perform a process of moving currently stored elasticity information such as Young's modulus according to tracking.

In addition, in Example 1, although the case where the range of the stress interval was set to 10 intervals with a width of 0.1 kPa was described as an example, the range of the stress interval to be allocated is made narrower and the number of intervals is set larger. By doing so (for example, 0.01 kPa width and 100 sections, etc.), the Young's modulus of the region outside the ROI can be obtained with higher accuracy.
In the first embodiment, the stress in the measurement point and the ROI is used as the measurement compression condition and the representative measurement compression condition obtained from the measurement compression condition. Reflects the state of compression, such as the amount of displacement measured by the unit 12 (including integration from zero displacement) and the stress transmitted in the ROI derived based on the pressure of the compression measured by the pressure measuring unit 17 Various types of information can also be used.

  As described above, in the first embodiment, whether or not the elasticity information of the living tissue (for example, Young's modulus) is displayed as an image is determined by the compression condition evaluation unit 18 in a state where the living tissue is actually pressed. Although it is determined and selected according to the measurement compression condition, the criterion for determining whether or not imaging is possible is not limited to this. For example, it is possible to determine whether or not such imaging is possible based on a reference value set by the examiner. Hereinafter, the case where the image availability is determined based on the reference value set by the examiner will be described as a second embodiment. The basic configuration of the ultrasonic diagnostic apparatus according to the second embodiment is the same as that of the above-described first embodiment (FIG. 1), and only the specific configuration of the second embodiment will be described below.

In the second embodiment, the compression condition evaluation unit 18 determines whether the current time at the measurement point or the past measurement compression condition (for example, stress) satisfies a preset reference compression condition, and satisfies the reference compression condition. For each measurement point, the current time or past elasticity information (for example, Young's modulus) is selected as elasticity information for generating an elasticity image.
Therefore, in the second embodiment, first, the reference compression condition is input and set by the examiner from the device control interface unit 19 to the compression condition evaluation unit 18. The reference compression condition is a threshold set in advance for measurement compression conditions such as stress and strain in order to image the Young's modulus of the living tissue for use by the examiner in actual diagnosis. The set reference compression condition is displayed on the B-mode image shown in FIG. 2 or the elastic image shown in FIG.
Then, the compression condition evaluation unit 18 takes in the elastic modulus data (numerical data of elastic modulus) at each measurement point and the numerical data of stress at each measurement point from the elastic information calculation unit 13. Example 2 shows a case where stress is used as a measurement compression condition for evaluating the degree of compression.

Here, as Example 2, a reference stress range is set, and an image of the entire region being displayed (observed) is generated based on elasticity information (for example, Young's modulus) measured within this range. The case where it does is demonstrated.
In this case, the compression condition evaluation unit 18 sets a stress range that is a reference for whether or not imaging is possible based on the reference compression condition input by the examiner from the device control interface unit 19. That is, a stress range in which the input reference stress σs is given a certain width, for example, a ± 10% stress range (0.9 × σs to 1.1 × σs) across the reference stress σs is used as the reference compression. Set as a condition. At that time, the ratio of the width to the reference stress σs is not particularly limited. Note that such a stress range may be directly input as the reference compression condition. Alternatively, it is possible to set the input reference stress σs as the reference compression condition as it is, not the stress range.

  When the reference compression condition is set in this way, the compression condition evaluation unit 18 next determines whether or not the current time or past stress at the measurement point has a value corresponding to the reference compression condition. When the stress is in the above stress range (0.9 × σs to 1.1 × σs), the Young's modulus value measured at that time is gray-scaled by monochrome luminance or hue and mapped as an elastic image. Then, the compression condition evaluation unit 18 sends a command to the elasticity information processing unit 14 to output and display the color elasticity image output from the color scan converter 15 on the image display 10 (for example, elasticity as shown in FIG. 3). Equivalent to an image being displayed). In the following explanation, it is said that the state where the stress at the measurement point at the current time or the past has a value corresponding to the reference compression condition is referred to as the reference compression condition, and the stress corresponds to the reference compression condition. It is said that it does not meet the standard compression condition.

  As a result, by changing the strength of the compression on the living tissue of the subject, an elastic image based on the Young's modulus of the measurement point that satisfies the reference compression condition is generated with the entire region being displayed (observed) as the region of interest. And can be displayed in real time. At that time, when the compression operation is repeated, if the stress at a certain measurement point satisfies the reference compression condition again, it is possible to update the elastic image with the value of the Young's modulus measured at that time. .

In order to estimate the Young's modulus of the measurement point at the reference stress σs, the measurement result of the Young's modulus in the negative 10% stress range (0.9 × σs to σs) and the positive 10% stress range (σs It is also possible to obtain the Young's modulus at the reference stress σs between them by linear interpolation, for example, from the measurement result of Young's modulus at ˜1.1 × σs). According to this method, the measurement result of the Young's modulus under the reference compression condition can be obtained with higher accuracy.
At that time, the past two Young's modulus measurement results closest to the reference stress σs are obtained by dividing the negative 10% stress range (0.9 × σs to σs) and the positive 10% stress range (σs to 1.1). Xσs) may be extracted one by one, and the Young's modulus value interpolated therefrom may be held as a measurement result. Furthermore, when a measurement result closer to the reference stress σs is obtained, the interpolation result may be updated as needed.

  In addition, a specific region of interest (ROI) is set instead of the entire region being displayed (observed), and based on Young's modulus (as an example, an average value) at a measurement point that satisfies the reference compression condition in the ROI It is also possible to generate and display an elastic image. At that time, the average value of the Young's modulus may be displayed on the B-mode image shown in FIG. 2 or the elastic image shown in FIG. This display may be continued until the average value of the Young's modulus is updated when the measurement point in the ROI satisfies the reference compression condition again, and then the updated average value may be displayed.

Here, also in Example 2, as in the case 1-1 of Example 1 described above, even if the stress at the current time satisfies the reference compression condition at a certain measurement point, the stress at the current time at another measurement point is In some cases, the reference compression condition is not satisfied, and in this case, the measurement point that does not satisfy the reference compression condition is not provided with either monochrome luminance or hue, and the Young's modulus image is not displayed (see FIG. 3). Equivalent to the display state shown).
That is, also in Example 2, when an elastic image is generated based on the Young's modulus value at a measurement point that satisfies the reference compression condition only at the current time, the measurement point at which the stress at the current time does not satisfy the reference compression condition No image is displayed for.
Therefore, similarly to the above-described embodiment 1-2 of Example 1, not only the current time but also information on the elastic modulus (for example, Young's modulus) when the reference compression condition has been satisfied in the past at the measurement point is stored. Thus, it is possible to generate an elastic image based on the latest Young's modulus value that satisfies the reference compression condition at the measurement point, or the average value of Young's modulus measured at a plurality of points in the past. Thereby, it is also possible to generate and display an elastic image based on the Young's modulus value for the entire region of the display image (observation image) (for example, a state in which an elastic image as shown in FIG. 4 is displayed). Equivalent). In the second embodiment, a buffer that can store a plurality of past measurement results in addition to the measurement result at the current time may be defined in the same manner as in the first and second aspects of the first embodiment. .

  In the second embodiment described above, for example, the generated elasticity image is displayed, and a graph image showing the relationship between the measurement compression condition and the elasticity information is created and displayed on the image display 10 to display the reference compression condition. It may be set on the image. As an example, it is possible to display the relationship between the stress and elastic modulus of the living tissue as shown in FIG. 7, and to set the reference compression condition based on this display. Accordingly, it is possible to set the reference compression condition while adjusting the elasticity of the living tissue under a predetermined stress in real time from the generated elasticity image.

In this case, the compression condition evaluation unit 18 plots the relationship between the stress and the elastic modulus based on the numerical data of the stress at each measurement point and the elastic modulus data (the elastic modulus numerical data) at each measurement point. Is generated and displayed on the image display 10. FIG. 7 is a display example of the created graph image. In this case, the relationship between the stress and the elastic modulus is displayed for the tissue with a large nonlinearity and the tissue with a small nonlinearity.
As shown in FIG. 7, a slide bar 70 that can slide in the axial direction is displayed on the stress axis that is the horizontal axis. The slide bar 70 indicates a reference compression condition, and the reference compression condition can be set to a desired value on the stress axis of the slide bar 70 by sliding the slide bar 70 along the stress axis. It is like that. Then, the measurement result of the elasticity information (for example, Young's modulus) at the measurement point that satisfies the reference compression condition set by the position of the slide bar 70 is mapped in real time and displayed as an elasticity image.
Therefore, it is possible to adjust the reference compression condition while checking the elasticity image displayed in real time according to the set reference compression condition for each of the tissue having a large nonlinearity and the tissue having a small nonlinearity, and the examiner uses it for the actual diagnosis. Therefore, it is possible to easily and reliably image the optimal Young's modulus state of the living tissue.

The slide bar shows a stress range in which the above-described reference stress σs is given a certain width according to the set reference compression condition (for example, a stress range of ± 10% across the reference stress σs). A predetermined range on the stress axis may be covered and displayed, or may be displayed crossing the stress axis so as to indicate the reference stress σs itself. Also, a plurality of slide bars may be displayed so that the reference stress σs and the stress range can be individually set. As an example, FIG. 7 shows a slide bar 70 representing a stress range in which a certain width is given to the reference stress σs. In such a slide bar 70, the center line indicated by a broken line in the figure indicates the value of the reference stress σs, and the boundary line indicated by a solid line on both sides in the stress axis direction across the center line indicates the upper limit value of the stress range. And the lower limit.
In either case, the operation of the slide bar 70 may be performed manually by the examiner via the device control interface unit 19 or the like, but may be automatically performed by the compression condition evaluation unit 18 or the like.

  Further, when the slide bar 70 is slid along the stress axis, in addition to or in place of the elastic image as described above, the distribution of Young's modulus values in the ROI and the entire region being displayed (observed) is a histogram. May be displayed. In this case, the statistical feature amount (average value, variance value, etc.) of the histogram may also be analyzed and displayed simultaneously with the histogram.

  Furthermore, in Example 2 described above, when the ROI is input and set by the examiner from the device control interface unit 19 to the compression condition evaluation unit 18, the value of the Young's modulus in the ROI is obtained. The relationship between stress and Young's modulus may be plotted, and a curve that best approximates may be displayed by a least square method or the like, and a feature quantity such as a nonlinear parameter representing the nonlinearity may be analyzed.

  It is also possible to switch the generation of the elastic image at the timing when the display image is frozen in the ultrasonic diagnostic apparatus. Hereinafter, a case where the image generation is switched by the freeze will be described as a third embodiment. . The basic configuration of the ultrasonic diagnostic apparatus according to the third embodiment is the same as that of the first embodiment (FIG. 1) and the second embodiment described above, and only the specific configuration of the third embodiment will be described below.

  In Example 3, the compression condition evaluation unit 18 newly selects elasticity information for generating an elasticity image to be displayed on the image display 10 when the elasticity image displayed on the image display 10 is frozen. The elastic image generated based on the newly selected elasticity information is displayed on the image display 10. For example, in Example 3, the Young's modulus value of the region consisting of measurement points satisfying the representative measurement compression condition or the reference compression condition at the current time in Example 1 (Aspects 1-2) and Example 2 described above is used. Continue to display the based image in real time. Then, when a freeze command is given to the ultrasonic diagnostic apparatus to freeze the display image, the Young's modulus storage information when the representative measurement compression condition or the reference compression condition has been met at the measurement point in the past is stored at the current time. Is configured to generate an elastic image based on the Young's modulus value for an area consisting of measurement points that are not displayed.

  In the third embodiment, when the elastic image displayed on the image display 10 is frozen, the compression condition evaluation unit 18 continuously reads the elastic image generated up to the freeze to the image display 10. By doing so, the elastic image can be displayed on the image display 10 as a moving image. In this case, when a freeze command is given to the ultrasonic diagnostic apparatus, the cine-memory unit 20 stores a predetermined number of temporally continuous elasticity images acquired until the freeze. The elastic image stored in the cine memory unit 20 is continuously read out so that it can be displayed on the image display 10 as a moving image.

  In addition to or in place of giving such a freeze command, when an elastic image having a certain area or more is generated for all displayable image areas, the elastic image ( Still image) may be stored in the cine memory unit 20.

  In the first embodiment, the second embodiment, and the third embodiment described above, in addition to the elasticity information obtained in real time at the current time (for example, Young's modulus), the measurement results of past elasticity information are also reflected in the displayed elasticity image. Is done. Therefore, the stored past elasticity information and the elasticity information at the current time are the elasticity information obtained from the same measurement section (ultrasonic scanning plane), in other words, the current time and the past elasticity information. It is necessary to ensure that is obtained from the same measurement point. For this reason, in the present embodiment, the compression condition evaluation unit 18 determines that the current elasticity information and the past elasticity information at the measurement point are obtained from the same measurement point, for example, the similarity between a pair of frame data. This is ensured by evaluating or monitoring the displacement of the probe 2. Therefore, as a method for ensuring the identity of the measurement cross section, a method for evaluating the similarity of images between two consecutive frames and a method for monitoring the displacement of the probe 2 are described below. To do. The basic configuration of the ultrasonic diagnostic apparatus according to the fourth embodiment is the same as that of the first embodiment (FIG. 1), the second embodiment, and the third embodiment.

As one of the methods in the image recognition technique for monitoring that the measurement cross section does not change using the correlation coefficient, for example, there is a method of evaluating the similarity between two images using the correlation coefficient. According to this method, it can be evaluated that the correlation is higher as the correlation coefficient is larger, and the correlation is lower as the correlation coefficient is smaller.
Therefore, the correlation coefficient of the B-mode image (that is, the measurement cross section) of the two frames of the current time and one frame in the past is calculated, and if the correlation coefficient is greater than a certain threshold value, both images are correlated and measurement is performed. It can be determined that the identity of the cross section is secured. On the other hand, if the correlation coefficient is smaller than the threshold value, it can be determined that there is no correlation between the two images, the measurement cross section changes, and the identity is not ensured. By repeating this every time a frame is updated, it is possible to determine the correlation between the current time and the B-mode images of a plurality of past frames, and to continuously ensure the identity of these measurement sections. Such processing may be performed by, for example, the compression condition evaluation unit 18, but may be performed by providing other processing means or a separate processing means therefor.

A method of ensuring the identity of the measurement cross section using displacement information obtained from a sensor attached to the probe 2 is also conceivable.
As one of the latest ultrasonic diagnostic technologies, a sensor is attached to the probe 2 of the ultrasonic diagnostic apparatus, and information such as the position, displacement, angle, and acceleration of the probe 2 at the current time is detected in real time. Is possible.
Therefore, if this technique is applied, it is possible to determine whether the measurement cross section is held or has changed by monitoring changes in the position and angle of the probe 2 at the current time.
In this case, a magnetic sensor can be assumed as the sensor, but the type of the sensor is not particularly limited as long as information such as the position, displacement, angle, and acceleration can be acquired.
Moreover, based on the motion recognition technique which recognizes operation | movement from the image image | photographed with the video camera, the method of ensuring the identity of a measurement cross section may be sufficient.

  In addition, when it is determined that the measurement cross section changes by these methods and the identity is not secured, measurement of elasticity information (as an example, Young's modulus) at all measurement points including past measurement result data The result should be cleared (initialized). As a result, it is possible to reliably ensure the identity of the measurement cross sections.

  As described above, according to the first to fourth embodiments of the present invention, the measurement time is selected for each measurement point according to the current time applied to each measurement point or the measurement compression condition (representative measurement compression condition or reference compression condition) before the current time. Elasticity images such as Young's modulus obtained based on compression conditions of the same size are used because the elasticity images generated based on the elasticity information (for example, Young's modulus) before and after the current time are used. Information, in other words, tissue elasticity response can be displayed and observed in real time as an image. Thereby, for example, a difference in response due to hardness when the strength of compression applied to the living tissue is changed can be observed with an image, and objective and definitive tissue differentiation can be performed. Further, it is not necessary to select an elastic image suitable for diagnosis, and the burden on the examiner is reduced.

In the first to fourth embodiments described above, the elastography technique for acquiring elasticity information by compressing the target tissue has been described as an example. However, the elastic image generation method of the present invention is, for example, an excitation image. It can also be applied to elasticity information obtained by methods such as Y. Yamakoshi et al: Ultrasonic Imaging of Internal Vibration of Soft Tissue under Forced Vibration, IEEE Trans UFFC 1990; 37; 45-53. .
Alternatively, even in dynamic elastography, since the stress distribution corresponding to the inside of the living body is generated by pushing the probe 2 to some extent, the same effect can be obtained by applying the elastic image generating method of the present invention. Regarding the technology of dynamic elastography, “QUANTITATIVE ASSESSMENT OF BREAST LESION VISCOELASTICITY: INITIAL CLINICAL RESULTS USING SUPERSONIC SHEAR IMAGING” MICKAEL TANTER et al: Ultrasound in Med. & Biol., Vol.34, No.x, pp.xxx, 2008 World Federation for Ultrasound in Medicine & Biology and “ACOUSTIC RADIATION FORCE IMPULSE ELASTOGRAPHY FOR THE EVALUATION OF FOCAL SOLID HEPATIC LESIONS: PRELIMINARY FINDINGS” SEUNG HYUN CHO et al: Ultrasound in Med. & Biol., Vol.36, No.2, pp .202-208,2010 You can refer to World Federation for Ultrasound in Medicine & Biology.
Further, for example, color Doppler when generating a blood flow image also depends on compression. Therefore, in this case, it is also possible to apply the elastic image generation method of the present invention so that the color Doppler color is applied only when the standard compression condition is satisfied.
In addition, images based on real-time Young's modulus values that do not take into account differences in stress conditions, and Young's modulus at measurement points that satisfy the stress conditions (representative measurement compression conditions and reference compression conditions) according to the elastic image generation method of the present invention An image based on the value of may be displayed on two screens.

DESCRIPTION OF SYMBOLS 1 Subject 2 Probe 3 Transmission circuit 4 Transmission / reception control circuit 5 Reception circuit 6 Phased addition circuit 7 Signal processing part 8 Black and white scan converter 9 Switching addition part 10 Image display 11 Frame data acquisition part 12 Displacement measurement part 13 Elastic information Calculation unit 14 Elastic information processing unit 15 Color scan converter 16 Pressure sensor 17 Pressure measurement unit 18 Compression condition evaluation unit 19 Device control interface unit 20 Cine memory unit

Claims (14)

Based on a reflected echo signal obtained by transmitting ultrasonic waves from the probe, an elasticity information calculation unit that obtains elasticity information of a living tissue at a plurality of measurement points in an image region and measurement compression conditions at the plurality of measurement points; ,
An image display for displaying an elasticity image generated based on the elasticity information;
The elasticity information for generating the elasticity image to be displayed on the image display is selected according to the measurement compression condition at the current time or before the current time, and the selected current time and the elasticity information before the current time An ultrasonic diagnostic apparatus comprising: a compression condition evaluation unit that causes the image display to display the elasticity image at the plurality of measurement points generated based on the measurement point.   The compression condition evaluation unit selects the elasticity information for generating the elasticity image to be displayed on the image display from the elasticity information at the current time, and at the current measurement point where the elasticity information is selected. 2. The measurement point is selected for each measurement point from the current time at the measurement point where the elasticity information is not selected or the elasticity information before the current time according to the measurement compression condition of time. Ultrasound diagnostic equipment.   The ultrasonic diagnostic apparatus according to claim 2, wherein the measurement point for which the elasticity information is selected is included in a region of interest set in the image region.   The compression condition evaluation unit, the elasticity information for generating the elasticity image to be displayed on the image display, according to the measurement compression conditions at the current time at all the measurement points in the image area, 2. The ultrasonic diagnostic apparatus according to claim 1, wherein selection is made for each measurement point from the elasticity information at the current time or before the current time at all measurement points.   The compression condition evaluation unit obtains a representative measurement compression condition representing the measurement compression condition from the measurement compression condition obtained by the elasticity information calculation unit, and the measurement compression condition at the current measurement time or before the current time The elasticity information for generating the elasticity image of the elasticity information at the current time or before the current time for each of the measurement points that satisfy the representative measurement compression condition. The ultrasonic diagnostic apparatus according to claim 1, wherein:   The representative measurement compression condition is obtained based on an average value of the measurement compression conditions at the current time at the measurement points in the region of interest set in the image region or all the measurement points in the image region. The ultrasonic diagnostic apparatus according to claim 5, wherein the apparatus is an ultrasonic diagnostic apparatus.   The compression condition evaluation unit determines whether or not the measurement compression condition at a current time or before the current time at the measurement point satisfies a preset reference compression condition, and for each measurement point that satisfies the reference compression condition, 2. The ultrasonic diagnostic apparatus according to claim 1, wherein the elasticity information for generating the elasticity image is selected as the elasticity information at a current time or before the current time. The compression condition evaluation unit creates a graph image indicating the relationship between the measurement compression condition and the elasticity information, and displays the graph image on the image display device.
The ultrasonic diagnostic apparatus according to claim 7, wherein the reference compression condition is set on the graph image.   The compression condition evaluation unit smoothes the elasticity information before the current time at the measurement point where the elasticity information is selected, or smoothes the elasticity information before the current time and the current time, The ultrasonic diagnostic apparatus according to claim 1, wherein the elasticity image is displayed on the image display unit based on the elasticity information after processing.   The compression condition evaluation unit newly selects the elasticity information for generating the elasticity image to be displayed on the image display when the elasticity image displayed on the image display is frozen, and newly The ultrasonic diagnostic apparatus according to claim 1, wherein the elastic image generated based on the selected elastic information is displayed on the image display.   When the elastic image displayed on the image display is frozen, the compression condition evaluation unit causes the image display to continuously read the elastic image generated up to the freeze. The ultrasonic diagnostic apparatus according to claim 1, wherein an elastic image is displayed on the image display as a moving image.   The compression condition evaluation unit evaluates the similarity between a pair of the frame data that the elasticity information at the current time at the measurement point and the elasticity information before the current time are obtained from the same measurement point. The ultrasonic diagnostic apparatus according to claim 1, wherein the ultrasonic diagnostic apparatus is secured by monitoring the displacement of the probe.   The compression condition evaluation unit gives the elasticity information to generate black and white luminance or hue to the elasticity information for generating the elasticity image to be displayed on the image display, and causes the image display to display the elasticity image. The ultrasonic diagnostic apparatus according to claim 1, wherein the ultrasonic diagnostic apparatus is characterized in that Based on the reflected echo signal obtained by transmitting ultrasonic waves to the biological tissue, the elasticity information of the biological tissue at a plurality of measurement points in the image region and the measurement compression conditions of the plurality of measurement points are obtained,
The elasticity information for generating the elasticity image to be displayed on the image display is selected according to the measurement compression condition at the current time or before the current time,
A method of generating an elasticity image, comprising: generating the elasticity images at the plurality of measurement points based on the selected current time and the elasticity information before the current time.

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